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关键词： Solid modeling   Insulated gate bipolar transistors   Finite element analysis   Analytical models   Thermal analysis   Electronic packaging thermal management   Heat transfer   Insulated-gate bipolar transistor (IGBT)   reliability   temperature dependent   thermal model   three dimensional (3-D)  

摘要： With the development of power electronics converters (PECs), the thermal properties of high-power insulated-gate bipolar transistor (IGBT) module are of significant importance in the reliability analysis, thermal design, and management of PECs. However, the present commonly used three-dimensional (3-D) thermal network model and still has limitations in accurately obtaining the junction temperature of IGBT modules. Particularly under high-temperature conditions, its performance is not ideal. This article proposes a 3-D thermal network model considering the temperature effect of constituent materials, which has been efficiently obtained using four sets of finite-element method (FEM) transient thermal simulation. By employing a two-step parameter extraction (TPE) method, the thermal parameters including the conductance and capacitance of crucial nodes are fully identified based on the reconstruction matrix of virtual temperature. In addition, the identified parameters are proven to reflect the temperature effect of materials with significant physical implications, which have also been discussed under various boundary conditions, e.g., temperature and cooling. The proposed 3-D temperature-dependent thermal model has been validated through FEM simulation and experiments, which shows satisfying performance in predicting the thermal behaviors under the whole-temperature conditions with an error within 1.2%.

关键词： ETM coupling field   Junction temperature   PINN   Numerical calculation   Data-model fusion  

摘要： The electric-thermal-mechanical (ETM) multi-physics coupling fields commonly exists in power electronic devices such as insulate-gate bipolar transistor (IGBT), which dominates the evolution of key state variables inside the components. Among them, the junction e and electric potential of the chip layer, as the dependent variables of various lifetime physical models, directly affect its remaining service life and health status. Aiming at the problem that the key physical variables inside the IGBT are difficult to monitor and predict, this paper first integrates and establishes the ETM coupling partial differential equations (PDEs) inside the IGBT, then accordingly proposes an accurate numerical calculation method for coupled physical fields based on ETM-physicsinformed neural networks (ETM-PINN).Through relevant simulation verification, it can not only realize the numerical calculation of the chip layer junction temperature and electric potential field without data, but also perform multi-physics predictive calculation with reduced accuracy in the absence of the key coefficients in PDEs. In the presence of additional physical field data, it can also perform data-model fusion calculations to further improve the solution accuracy.

关键词： Circuit faults   Fault diagnosis   Capacitors   Voltage   Accuracy   Switches   Mathematical models   Feature reconstruction (FR)   full power condition   modular multilevel converter (MMC)   multiple fault diagnosis   recurrent neural network (RNN)  

摘要： The modular multilevel converter (MMC) open-circuit fault diagnosis under full power condition has become a challenging problem. Especially, when MMC operates under low-power conditions, there are significant fluctuations in capacitor voltage and the existing fault diagnosis strategies face difficulties in selecting appropriate thresholds. This article proposes a multiple open-circuit fault diagnosis strategy for MMC using the feature reconstruction-recurrent neural network (FR-RNN). In this method, the dominant characteristics of the theoretical and actual capacitor current of the submodules (SMs) are presented as the preferred feature set. The auxiliary mathematical feature based on capacitor current was screened using maximal information coefficient (MIC), and then, the selected auxiliary mathematical feature and the preferred feature set were inputted into the RNN for FR to realize fault diagnosis based on the optimal feature set. The proposed strategy can directly achieve accurate fault localization and fault-type judgment of SM faults without additional detection steps and diagnostic delay. In addition, the determined optimal feature set greatly simplifies the network computation, thus avoiding deviation caused by multidimensional and redundant features on the diagnosis outputs. Simulation and experimental studies confirm the effectiveness of strategy.

关键词： electric vehicles   power convertors   reliability  

摘要： The reliability of power electronic converters is one of the essential issues in designing of electric vehicles. This paper estimates the lifetime of the boost converter switch by Semikron and Coffin-Manson models for two common failure mechanisms of Bond wire and Base plate solder, respectively. Four mission profiles based on the Artemis standard are applied to hybrid electrical vehicle model to determine unidirectional output power. Kharitonov's theory is used to design a robust controller to handle the uncertainty raised by different power cycles of the electric vehicle and the parameters of the converter during simulation. Stability of converter is achieved during simulation by identifying simple proportional integral controller coefficients with Kharitonov's theorem. A prototype 230 W boost converter is designed and utilized to validate average model and switch loss calculation relationships. The lifetime results indicate that the number of cycles, and the average and the maximum junction temperature have a more impact than the duration of the drive cycle on the lifetime of the converter. A mixed mission profile is considered to investigate the effect of sudden change in driving modes and speed on total consumed life and lifetime to enhance the study's applicability. Lifetime of switch is decreased significantly in mixed mode in comparison with other mission profiles in the same driving time. Furthermore, the motorway mission profile has 53%, 39.6%, and 160% less total consumed life in comparison with the urban, rural and mixed mission profiles, respectively. In addition, the effect of ambient temperature changes on IGBT lifetime has been investigated for four mission profiles. While motorway had the least total consumed life in 25 degrees C, the urban had better performance in comparison with other mission profiles from 25 to 55 degrees C.

关键词： fiber optic sensors   power electronics   IGBT   junction temperature   multipoint sensing  

摘要： This study investigates the feasibility of using fiber Bragg grating (FBG) sensors for multipoint thermal monitoring of several power semiconductor devices (PSDs), such as insulated gate bipolar transistors (IGBTs), and rectifiers assembled on a common heatsink in a three-phase inverter. A novel approach is proposed to integrate FBG sensors beneath the baseplates of the IGBT modules, avoiding the need for invasive modifications to the device structure. By strategically positioning multiple FBG sensors, accurate temperature profiles of critical components can be obtained. The experimental results demonstrate the effectiveness of the proposed method, with the temperature measurements from FBG sensors closely matching those obtained using thermal infrared (IR) cameras within +/- 1.1 degrees C. This research highlights the potential of FBG sensors for reliable and precise thermal management in power electronic systems, contributing to improved performance and reliability.

关键词： Insulated gate bipolar transistors   Switches   Heating systems   Capacitors   Breakdown voltage   Capacitance   Ceramics   Heatsink-to-ground voltage   insulated gate bipolar transistors (IGBTs) insulation protection   IGBT insulation voltage   modular multilevel converter   submodule stray capacitor model  

摘要： In practical modular multilevel converter (MMC) engineering, the dc voltage can be as high as tens to hundreds of kV, while the insulated gate bipolar transistors (IGBTs) isolation voltage is only several kV. The extreme high voltage of MMC can easily destroy the ceramic layers of the IGBT. To assess the IGBT insulation voltages and help design insulation protection measures in the early design stage of MMC, this article proposes a submodule stray capacitor based calculation method for IGBT insulation voltages. First, the switching-states and the stray capacitor model of submodules are introduced. Then, the IGBT insulation voltages are derived in detail, and the voltage characteristics under normal and fault conditions are analyzed. After that, the effect of the heatsink-to-ground capacitance on the maximum IGBT insulation voltages is discussed. The proposed method has a good accuracy with most relative errors less than 5% (calculation versus simulation) and 20% (calculation versus experiment). To protect the insulation safety of IGBTs, this article also gives a design example of the maximum heatsink-to-ground stray capacitance. The proposed method can not only guide the IGBT insulation protection design, but also provide the model reference and the heatsink-to-ground voltage estimation for the EMI researches of MMC.

关键词： Logic gates   Monitoring   Germanium   Transient analysis   Resistance   Insulated gate bipolar transistors   Voltage   Chip open-circuit failure   condition monitoring   fall time of gate voltage   multichip insulated gate bipolar transistor (mIGBT) modules  

摘要： In high-power converters, multichip insulated gate bipolar transistor (mIGBT) modules, consisting of multiple parallel chips, are widely used to obtain the desired large current capacity. For evaluating the reliability of power converters, it is significant to monitor chip open-circuit failure of mIGBT modules caused by bond-wires lift off. This article proposes that the fall time of gate-voltage ( t(gf)) is adopted to monitor chip open-circuit failure. Because the gate input capacitance of mIGBT modules suddenly decreases when the chip open-circuit fails, resulting in a remarkable decrease of t(gf). A double-pulse experimental platform is developed to verify the feasibility and sensitivity of the proposed method. Experimental results show that t(gf) jumps and decreases immediately when the chip open-circuit failure occurs, and the proposed method has a strong immunity to variations in operating conditions. In addition, the proposed method only requires measuring variations in gate voltage, and the monitoring circuit can be integrated into the gate drive circuit or used as a plug-and-play device. Thus, the proposed method is safe, less invasive, and easy to implement, which can provide a way for the reliability evaluation of mIGBT modules.

关键词： LLC resonant converter   current sensor (CS)   IGBT open circuit (OC) fault   adaptive sliding mode observer  

摘要： LLC resonant converters have emerged as essential components in DC charging station modules, thanks to their outstanding performance attributes such as high power density, efficiency, and compact size. The stability of these converters is crucial for vehicle endurance and passenger experience, making reliability a top priority. However, malfunctions in the switching transistor or current sensor can hinder the converter's ability to maintain a resonant state and stable output voltage, leading to a notable reduction in system efficiency and output capability. This article proposes a fault diagnosis strategy for LLC resonant converters utilizing a reduced-order interval sliding mode observer. Initially, an augmented generalized system for the LLC resonant converter is developed to convert current sensor faults into generalized state vectors. Next, the application of matrix transformations plays a critical role in decoupling open-circuit faults from the inverter system's state and current sensor faults. To achieve accurate estimation of phase currents and detection of current sensor faults, a reduced-order interval sliding mode observer has been designed. Building upon the estimation results generated by this observer, a diagnostic algorithm featuring adaptive thresholds has been introduced. This innovative algorithm effectively differentiates between current sensor faults and open switch faults, enhancing fault detection accuracy. Furthermore, it is capable of localizing faulty power switches and estimating various types of current sensor faults, thereby providing valuable insights for maintenance and repair. The robustness and effectiveness of the proposed fault diagnosis algorithm have been validated through experimental results and comparisons with existing methods, confirming its practical applicability in real-world inverter systems.

关键词： bridge circuits   insulated gate bipolar transistors   power semiconductor devices   semiconductor device reliability   short-circuit currents  

摘要： Insulated gate bipolar transistors (IGBTs) serve as the pivotal components within power conversion systems, and given the harsh conditions they endure, evaluating their aging is of paramount importance. Traditional offline aging monitoring method are relatively complex. Based on the conduction voltage drop as the characteristic quantity of IGBT aging, a simpler technique for extracting this parameter is presented, facilitating the assessment of IGBT aging status. Incorporating the working principle of the IGBT bridge-arm short-circuit, a conduction voltage drop model has been established. A composite aging electrical parameter is used to eliminate the impact of degradation in the bond wire of the current source device. By engineering a closed-loop gate drive circuit with adjustable voltage, the short-circuit current is maintained constant, thereby facilitating the acquisition of a consistent conduction voltage drop. A conduction voltage extraction circuit is proposed, in which a resistance-capacitance discharging time is equivalent to the conduction voltage drop to replace the analogue-to-digital circuit. By decreasing the amount of active zone of the chip in IGBT module for increased conduction voltage drop to simulate aging state, the proposed method with the driving circuit is experimentally validated as feasible and reliable.

关键词： degradation state assessment   Changing working conditions   insulated gate bipolar transistor (IGBT)   degradation state assessment   long short-term memory (LSTM)-autoencoder (AE)   long short-term memory (LSTM)-autoencoder (AE)   inter- pretability   inter- pretability   priori knowledge   priori knowledge   priori knowledge   inter- pretability   inter- pretability   inter- pretability   long short-term memory (LSTM)-autoencoder (AE)   priori knowledge  

摘要： Researches indicate that the insulated gate bipolar transistor (IGBT) module is a crucial yet failure-prone constituent of power electronic devices. As a result, assessing the degradation state of IGBT module is significant to guarantee safe device operation. However, existing studies are usually conducted under constant working conditions, which is inconsistent with the strong nonlinearity of the degradation process and strong coupling of parameters of the IGBT module caused by changing working conditions. Additionally, the designed models often lack interpretability, making it less credible. Some of them may even need to be processed with the full life data after the degradation state is obtained, which does not satisfy the requirements of online applications. Therefore, this article proposes an interpretable long short-term memory (LSTM)-autoencoder (AE) modeling method for degradation state assessment of IGBT modules under changing working conditions. First, the interpretability of the model is improved by designing a contrastive output structure. Then, by analyzing the characteristics of IGBT module degradation process, the properties of the degradation are summarized, and the prior knowledge is integrated into the model as a constraint to enhance the accuracy of the degradation state assessment and further improve the interpretability. Afterward, a variable working condition power cycle experiment system is designed and constructed to collect degradation data. Finally, the performance of the proposed method is verified. The results show that the degradation state extracted by the proposed method are more consistent with the theoretical analysis results, which can accurately assess the degradation state of IGBT modules.